Return function hashes

[jebonfig]

From what I understand, the evm.getFunctions() call only returns functions that appear in the functionHashes.json lookup. If the hash is not mapped in this file, it won't be returned.

Assuming the code is able to distinguish and parse out function hashes contained in a contract's bytecode without using the mapping file, could we add a function to return all function hashes in a contract? Maybe something like getFunctionHashes(): which returns `{'functionHash': 'functionSignature'}? (functionSignature would be null if couldn't be mapped)

If the mapping lookup is necessary for extracting the functions, how about adding an optional parameter to evm.getFunctions() for additional function hash -> signature mappings to check for in addition to the mapping file?